What might cause constant dull l-side testes pain for a weak, worse when sitting, unresponsive to presc. antibiotics for 6 days? thank you.

Genitourinary pains: It sounds like you have a problem with the genitourinary tract. It could be your prostate that's troubling you - because in a sitting position, there is pressure applied to that area. Alternatively, it could be a problem with the testis or the attached structures. The key would be 'what' other symptoms you have, what a physical exam might show, and relevant lab tests (urinalysis to start with).